Where extreme purity melting of certain metals and semiconductor materials is required, the difficulties with contaminants entering the melt from the material of the crucible have occasioned a number of different furnace arrangements and refining techniques. Considerable technology has been expended to construct crucibles for minimizing contamination of the materials from which they are constructed passing into a melt therein. Thus, for example, crucibles for melting highest purity silicon have been made from or lined with fused silica, silicon carbide, graphite, or similar high melting material that is essentially indifferent to silicon, to minimize melt contamination. However, less than satisfactory results have been achieved as these crucibles, when exposed to the heat required to melt their contents will transfer, even in small quantities, the crucible material to the melt thereby causing contamination thereto.